/*
  Copyright (c) 2010, 2011, Oracle and/or its affiliates. All rights reserved.

  The MySQL Connector/J is licensed under the terms of the GPLv2
  <http://www.gnu.org/licenses/old-licenses/gpl-2.0.html>, like most MySQL Connectors.
  There are special exceptions to the terms and conditions of the GPLv2 as it is applied to
  this software, see the FLOSS License Exception
  <http://www.mysql.com/about/legal/licensing/foss-exception.html>.

  This program is free software; you can redistribute it and/or modify it under the terms
  of the GNU General Public License as published by the Free Software Foundation; version 2
  of the License.

  This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
  without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  See the GNU General Public License for more details.

  You should have received a copy of the GNU General Public License along with this
  program; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth
  Floor, Boston, MA 02110-1301  USA
 
 */
package com.mysql.jdbc;

import java.sql.SQLException;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

public class ConnectionGroup {
	private String groupName;
	private long connections = 0;
	private long activeConnections = 0;
	private HashMap<Long, LoadBalancingConnectionProxy> connectionProxies = new HashMap<Long, LoadBalancingConnectionProxy>();
	private Set<String> hostList = new HashSet<String>();
	private boolean isInitialized = false;
	private long closedProxyTotalPhysicalConnections = 0;
	private long closedProxyTotalTransactions = 0;
	private int activeHosts = 0;
	private Set<String> closedHosts = new HashSet<String>();

	ConnectionGroup(String groupName){
		this.groupName = groupName;
	}
	
	public long registerConnectionProxy(LoadBalancingConnectionProxy proxy, List<String> localHostList){
		long currentConnectionId;

		synchronized (this){
			if(!this.isInitialized){
				this.hostList.addAll(localHostList);
				this.isInitialized = true;
				this.activeHosts = localHostList.size();
			}
			currentConnectionId = ++connections;
			this.connectionProxies.put(Long.valueOf(currentConnectionId), proxy);
		}
		this.activeConnections++;
		
		return currentConnectionId;
		
	}
	
	/* (non-Javadoc)
	 * @see com.mysql.jdbc.ConnectionGroupMBean#getGroupName()
	 */
	public String getGroupName(){
		return this.groupName;
	}
	
	/* (non-Javadoc)
	 * @see com.mysql.jdbc.ConnectionGroupMBean#getInitialHostList()
	 */
	public Collection<String> getInitialHosts(){
		return this.hostList;
	}
	
	/* (non-Javadoc)
	 * @see com.mysql.jdbc.ConnectionGroupMBean#getActiveHostCount()
	 */
	public int getActiveHostCount(){
		return this.activeHosts;
	}
	
	
	public Collection<String> getClosedHosts(){
		return this.closedHosts;
	}
	
	
	/* (non-Javadoc)
	 * @see com.mysql.jdbc.ConnectionGroupMBean#getTotalLogicalConnectionCount()
	 */
	public long getTotalLogicalConnectionCount(){
		return this.connections;
	}
	
	/* (non-Javadoc)
	 * @see com.mysql.jdbc.ConnectionGroupMBean#getActiveLogicalConnectionCount()
	 */
	public long getActiveLogicalConnectionCount(){
		return this.activeConnections;
	}
	/* (non-Javadoc)
	 * @see com.mysql.jdbc.ConnectionGroupMBean#getActivePhysicalConnectionCount()
	 */
	public long getActivePhysicalConnectionCount(){
		long connections = 0;
		Map<Long, LoadBalancingConnectionProxy> proxyMap = new HashMap<Long, LoadBalancingConnectionProxy>();
		synchronized(this.connectionProxies){
			proxyMap.putAll(this.connectionProxies);
		}
		Iterator<Map.Entry<Long, LoadBalancingConnectionProxy>> i = proxyMap.entrySet().iterator();
		while(i.hasNext()){
			LoadBalancingConnectionProxy proxy = i.next().getValue();
			connections += proxy.getActivePhysicalConnectionCount();
			
		}
		return connections;
	}
	
	/* (non-Javadoc)
	 * @see com.mysql.jdbc.ConnectionGroupMBean#getTotalPhysicalConnectionCount()
	 */
	public long getTotalPhysicalConnectionCount(){
		long allConnections = this.closedProxyTotalPhysicalConnections;
		Map<Long, LoadBalancingConnectionProxy> proxyMap = new HashMap<Long, LoadBalancingConnectionProxy>();
		synchronized(this.connectionProxies){
			proxyMap.putAll(this.connectionProxies);
		}
		Iterator<Map.Entry<Long, LoadBalancingConnectionProxy>> i = proxyMap.entrySet().iterator();
		while(i.hasNext()){
			LoadBalancingConnectionProxy proxy = i.next().getValue();
			allConnections += proxy.getTotalPhysicalConnectionCount();
			
		}
		return allConnections;
	}
	
	/* (non-Javadoc)
	 * @see com.mysql.jdbc.ConnectionGroupMBean#getTotalTransactionCount()
	 */
	public long getTotalTransactionCount(){
		// need to account for closed connection proxies
		long transactions = this.closedProxyTotalTransactions;
		Map<Long, LoadBalancingConnectionProxy> proxyMap = new HashMap<Long, LoadBalancingConnectionProxy>();
		synchronized(this.connectionProxies){
			proxyMap.putAll(this.connectionProxies);
		}
		Iterator<Map.Entry<Long, LoadBalancingConnectionProxy>> i = proxyMap.entrySet().iterator();
		while(i.hasNext()){
			LoadBalancingConnectionProxy proxy = i.next().getValue();
			transactions += proxy.getTransactionCount();
			
		}
		return transactions;		
	}

	
	public void closeConnectionProxy(LoadBalancingConnectionProxy proxy){
		this.activeConnections--;
		this.connectionProxies.remove(Long.valueOf(proxy.getConnectionGroupProxyID()));
		this.closedProxyTotalPhysicalConnections += proxy.getTotalPhysicalConnectionCount();
		this.closedProxyTotalTransactions += proxy.getTransactionCount();
		
	}
	
	public void removeHost(String host) throws SQLException {
		removeHost(host, false);
	}
	
	public void removeHost(String host, boolean killExistingConnections) throws SQLException {
		this.removeHost(host, killExistingConnections, true);

	}
	/* (non-Javadoc)
	 * @see com.mysql.jdbc.ConnectionGroupMBean#removeHost(java.lang.String, boolean, boolean)
	 */
	public synchronized void removeHost(String host, boolean killExistingConnections, boolean waitForGracefulFailover) throws SQLException {
		if(this.activeHosts == 1){
			throw SQLError.createSQLException("Cannot remove host, only one configured host active.", null);
		}
		
		if(this.hostList.remove(host)){
			this.activeHosts--;
		} else {
			throw SQLError.createSQLException("Host is not configured: " + host, null);
		}
		
		if(killExistingConnections){
			// make a local copy to keep synchronization overhead to minimum
			Map<Long, LoadBalancingConnectionProxy> proxyMap = new HashMap<Long, LoadBalancingConnectionProxy>();
			synchronized(this.connectionProxies){
				proxyMap.putAll(this.connectionProxies);
			}
			
			Iterator<Map.Entry<Long, LoadBalancingConnectionProxy>> i = proxyMap.entrySet().iterator();
			while(i.hasNext()){
				LoadBalancingConnectionProxy proxy = i.next().getValue();
				if(waitForGracefulFailover){
					proxy.removeHostWhenNotInUse(host);
				} else {
					proxy.removeHost(host);
				}
			}			
		}
		this.closedHosts.add(host);
	}
	
	
	public void addHost(String host){
		addHost(host, false);
	}
	
	
	/* (non-Javadoc)
	 * @see com.mysql.jdbc.ConnectionGroupMBean#addHost(java.lang.String, boolean)
	 */
	public void addHost(String host, boolean forExisting){
		
		synchronized(this){
			if(this.hostList.add(host)){
				this.activeHosts++;
			}
		}
		// all new connections will have this host
		if(!forExisting){
			return;
		}
		
		
		// make a local copy to keep synchronization overhead to minimum
		Map<Long, LoadBalancingConnectionProxy> proxyMap = new HashMap<Long, LoadBalancingConnectionProxy>();
		synchronized(this.connectionProxies){
			proxyMap.putAll(this.connectionProxies);
		}
		
		Iterator<Map.Entry<Long, LoadBalancingConnectionProxy>> i = proxyMap.entrySet().iterator();
		while(i.hasNext()){
			LoadBalancingConnectionProxy proxy = i.next().getValue();
			proxy.addHost(host);
		}
		
	}
	
}
